The Reference 6SN7 Thread

Apr 6, 2023 at 10:18 AM Post #8,581 of 10,668
The issues are most commonly referred to "SCP" (Snap, Crackle, Pop), but can also include a whistling, whining, or static sound. If the tube tests strong but sounds terrible, more likely than not you can restore some life to it with a resolder.

One of the most common problems with NOS Melz 1578's are that the solder is simply terrible in them. People get these highly touted tubes only to be disappointed by hearing such AWFUL noise coming from them. If you ever see anyone selling these (or other "grail) tubes for a song saying they're defective, don't be afraid to pick them up and try it - you could be very happy with the results!
I repaired plenty of Melz for other people as well as having a decent collection covering the golden years. 1953-1964, 1968 and 1969 are not too bad as well. I have also fixed many a Foton, Russian solder from that time period is the issue IMHO. On the Fotons some of the non ribbed versions started sounding better with a solder change as best I can recall.
 
Apr 6, 2023 at 11:39 AM Post #8,583 of 10,668
I also wonder if there's any benefit in doing a resolder regardless if the tube is noisy. I'd imagine once you got your technique nailed, there's little risk doing it.
And who's to say… if the tube sounds good already, maybe it'll sound gooder afterwards:thinking:
I go more by age of the tube and country of origin. I own many tubes from the fifties and some from the forties so I like to replace the solder on some of those before they start acting up. Tung Sol 5998's have shown issues as have some of the older Svetlana winged C's, (I own many from the fifties).
 
Apr 6, 2023 at 1:06 PM Post #8,584 of 10,668
I have a needle applicator on a little bottle of liquid flux. It assures the flux coats the inside of the pins and cleans the wire. Prior to that I would apply a drop or two with a very fine pick and capillary action would draw it in.
I use a 5 cc hypodermic syringe with a fairly small needle to inject Kester liquid rosin flux. Don't forget to flush the syringe/needle with alcohol after use, as the rosin will dry to a hard mass.
 
Apr 6, 2023 at 1:09 PM Post #8,585 of 10,668
I also wonder if there's any benefit in doing a resolder regardless if the tube is noisy. I'd imagine once you got your technique nailed, there's little risk doing it.
And who's to say… if the tube sounds good already, maybe it'll sound gooder afterwards:thinking:
Or perhaps, fix it until it's broke-----.
 
Apr 6, 2023 at 1:19 PM Post #8,586 of 10,668
I use a 5 cc hypodermic syringe with a fairly small needle to inject Kester liquid rosin flux. Don't forget to flush the syringe/needle with alcohol after use, as the rosin will dry to a hard mass.
I have never had an issue with the needle, there is a small cap that fits over the end. The little bottles are made for paints and the needle tip is small enough to go inside a pin.
 
Apr 6, 2023 at 10:06 PM Post #8,587 of 10,668
I began replacing the solder in 6sn7 equivalents because of @bcowen and the Fotons. :ksc75smile: The belief was that they needed a hundred hours of burn in to settle in. What was actually happening was the solder might get hot enough from constant use to help the pin connection. After replacing the solder in some of the tubes and running several tests I found the tube burn in was maybe ten hours. I carried this over to Melz tubes, and several power tubes. Some people used to reflow the solder, I began replacing it entirely trying to be sure the original solder did not fail again. My theory also proved to be correct when Mr. Cowen went back and tested Foton tubes he had burned in and they were still acting like they originally did.
See, I wish you'd told me that before I bought 370,000 of them trying to find a quiet one. Now I have this huge unneeded stash, and have to deal with @LobalWarming peering over the security fence every night looking for an easy way in. Tubes can be a pain at times. 🤣 🤣
 
Apr 6, 2023 at 10:12 PM Post #8,588 of 10,668
See, I wish you'd told me that before I bought 370,000 of them trying to find a quiet one. Now I have this huge unneeded stash, and have to deal with @LobalWarming peering over the security fence every night looking for an easy way in. Tubes can be a pain at times. 🤣 🤣
If 369,900+ of them are microphonic, noisy, or generally crappy, why not leave the fence ajar, allow LW to help himself? Save on storage costs / use ‘casualty / theft loss’ deduction …. 🤔😀
 
Apr 6, 2023 at 10:19 PM Post #8,589 of 10,668
If 369,900+ of them are microphonic, noisy, or generally crappy, why not leave the fence ajar, allow LW to help himself? Save on storage costs / use ‘casualty / theft loss’ deduction …. 🤔😀
'Cause he might mistakenly stumble on the 5,000 sq/ft bunker full of WE 300B's. 🤣
 
Apr 6, 2023 at 10:26 PM Post #8,590 of 10,668
If 369,900+ of them are microphonic, noisy, or generally crappy, why not leave the fence ajar, allow LW to help himself? Save on storage costs / use ‘casualty / theft loss’ deduction …. 🤔😀
I would take 20 or so off your hands for $15 each, I would charge you less but it is a lot of work to shift around better tubes to make space.😜
 
Apr 6, 2023 at 10:46 PM Post #8,591 of 10,668
I would take 20 or so off your hands for $15 each, I would charge you less but it is a lot of work to shift around better tubes to make space.**😜
** an excellent use of ‘opportunity cost’ pricing 👏.
 
Apr 7, 2023 at 4:34 PM Post #8,593 of 10,668
I would take 20 or so off your hands for $15 each, I would charge you less but it is a lot of work to shift around better tubes to make space.😜
That would leave me only 369,980 which would be slightly below minimum stash level. I’d love for you to help me out, but will have to decline this time. :stuck_out_tongue_closed_eyes: :stuck_out_tongue_closed_eyes:
 
Apr 7, 2023 at 4:41 PM Post #8,595 of 10,668
Ha, talk about selfish ;)
I know!!! One of these days he will want another amplifier in a cardboard cabinet and I will ignore him.🤪 48E6899E-F501-446C-BCE4-FCA5F465EFB5.jpeg
 

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